My favorite Xbox games that I played hours on end were...Fuzion Frenzy which was just so much better than the sequel...Breakdown, very cool FPS, definitely look at screenshotsProject Snowblind, another cool FPS similar to one of the James Bond games (in terms of gameplay)Halo which you can spend hours modding and patching maps, (find an app called HCE for your xbox)...Kung Fu Chaos, fun game very similar to power stoneCrazy Taxi 3Counter Strike (only xbox live)

Some good ones are:Halo and Halo 2Fable (Best action RPG)DOA: Ultimate (One of the best fighting games ever)Soul Caliber 2Red Dead RevolverGun (Short but fun action adventure)Final Fight: Streetwise (Yeah I know ill be getting flamed for this one)GTA: Double Pack and San AndreasLego Star Wars 1 and 2 (Kiddy but fun)The GodfatherScarface: The World Is Yours (I prefer this game to GTA)Half Life 2BlackThe Punisher